1. Field of the Invention
The present invention relates to an image deflection correction apparatus, and more particularly to an image deflection correction apparatus which corrects (prevents) an image deflection caused by the vibration in a camera.
2. Description of the Related Art
An image deflection correction apparatus of a television camera to correct an image deflection is well known in which a vibration proofing lens is arranged freely movably within a plane orthogonal to an optical axis in a photographing optical system, and if the vibration is applied to the camera (photographing optical system of the camera), the vibration proofing lens is driven by an actuator to cancel the image deflection (e.g., refer to Japanese Patent Application Laid-Open No. 2001-142103 and Japanese Patent Application Laid-Open No. 2003-107554). Also, other methods for correcting the image deflection are well known besides the method of employing the vibration proofing lens movable within the plane orthogonal to the optical axis. A correction amount of canceling the image deflection against the vibration applied to the camera (equivalent to a displacement amount of the vibration proofing lens if the vibration proofing lens is employed) is calculated, based on a deflection signal outputted from a deflection detection sensor such as an angular velocity sensor, by detecting the vibration applied to the camera with the deflection detection sensor.
Also, the deflection signal outputted as the vibration by the deflection detection sensor is generated by the vibration subjected to the image deflection correction and the vibration caused by an intentional operation of changing the photographing composition by the cameraman. The operation of changing the photographing composition may be the panning operation for changing the composition in the horizontal direction, the tilting operation for changing the composition in the vertical direction, or the operation for changing the composition in the oblique direction between horizontal and vertical directions. In this specification, the operation of changing the composition is generally referred to as the pan/tilt operation. This pan/tilt operation is not involved in the vibration subjected to the image deflection correction, and it is not preferable to make the image deflection correction for the deflection signal caused by the pan/tilt operation.
Conventionally, a system has been offered for automatically judging whether or not the camera (optical system) is in the pan/tilt operation, based on a deflection signal obtained from the deflection detection sensor, in which the camera switches to a proper mode of image deflection correction where the pan/tilt operation is active, if it is judged that the camera is in the pan/tilt operation. For example, it has been proposed that if it is judged that the camera is in the pan/tilt operation, the image deflection correction is stopped (the efficacy of the image deflection correction is reduced) to resolve an unnatural screen caused by the image deflection correction in the pan/tilt operation or the bad operability due to the pan/tilt operation (e.g., refer to Japanese Patent Application Laid-Open No. 2002-229089). A judgment (pan/tilt judgment) whether or not the camera is in the pan/tilt operation is made depending on whether or not the magnitude of the deflection signal from the deflection detection sensor exceeds a prescribed threshold continually for a certain period of time or more, for example.